Spreadsheet Formulas
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A spreadsheet formula is an equation that performs a calculation on the numbers, functions and values of one or more cells. A formula is associated with a cell or a cell range. It is accessed using the CellRange.Formula property.
Formula Types
| Formula Type | Description |
|---|---|
| Normal | Use the CellRange.Formula property to assign a formula to a cell or each cell in a range. Refer to the Formulas example section for more information on how to create formulas. |
| Shared | A shared formula can be used to optimize calculations and file size. A shared formula is the equivalent of applying the same formula to a cell range. Shared formula is created automatically when you assign a formula string to an array of cells. A specified formula is associated with each cell contained within the specified cell range. |
| Array | An array formula allows you to perform calculations with arrays of cells. Use the CellRange.ArrayFormula property or ArrayFormulaCollection.Add method to include array formulas in a worksheet. An array formula for a cell or cell range is accessible via the CellRange.ArrayFormula property. To find an array formula range that includes a particular cell, use the Cell.GetArrayFormulaRange method. For more information on array formulas, see the Array Formulas document. |
Formula Syntax
A formula is a string expression that begins with an equal (=) sign. A formula can contain the constants, operators, cell references, calls to functions, and names.
Consider the following formula, which calculates the mass of a sphere.
=4/3PI()(A2^3)*Density
- “4” and “3” are numeric constants. Although they are written as integers, the division operator (/) interprets them as being real numbers, i.e., 4.0 and 3.0. As a result, the calculation produces a precise result that is not rounded to an integer.
- “/” is the division operator.
- “PI()” results in a call to the PI function, which returns the value of π.
- “A2” is a cell reference, which returns the value within that specific cell.
- “3” is a numeric constant.
- “^” is the caret operator, which raises the left operand to the power of the right operand.
- Parentheses are used for grouping and changing the operator precedence.
- “” is the asterisk () operator, which performs multiplication.
- The Density is a defined name within the worksheet that can represent a cell range, a function or a constant.
The formula is calculated from left to right, according to the operator precedence. To change the order of calculation you can enclose a portion of the formula in parentheses.
Parts of a Formula
Calculation
To recalculate all formulas in a workbook, call the IWorkbook.Calculate method. The DocumentSettings.Calculation property provides access to calculation options. Calculation results are placed in the Range.Value property of corresponding cells.
You can also calculate a formula and leave the document unchanged by using the IWorkbook.Evaluate method.
Formula Engine
The FormulaEngine is an object that provides the capability to calculate and parse worksheet formulas. It includes a built-in formula parser, as well as the flexibility to evaluate formulas in any range of any worksheet. See the Formula Engine topic for more information.